The renditions rules are, as their name indicates, rules that are applied to the profile of a content, be it VOD or LIVE.
Go to the settings menu and choose renditions rules and create or edit one. The configuration popup is like this:
There you give a name to your rule, and select its characteristics. You can say that 1080p quality is only available in "x" country for example and so on. Apply for Live Stream. If you want to use it in VOD you need to create a category and assign it.
In Live the assignment of the rendition is under the profile:
In VOD, it is to assign the category with the rule and everything is configured